import java.util.LinkedList;
import java.util.Queue;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: 26727
 * Date: 2024-09-26
 * Time: 12:41
 */
class Solution10 {
    int[] dx = {1,-1,0,0};
    int[] dy = {0,0,1,-1};
    int m;
    int n;
    public void solve(char[][] board) {
        m = board.length;
        n = board[0].length;

        // 遍历边界
        for(int i = 0; i < m; i++) {
            if(board[i][0] == 'O') {
                bfs(board,i,0);
            }
            if(board[i][n-1] == 'O') {
                bfs(board,i,n-1);
            }
        }

        for(int j = 0; j < n; j++) {
            if(board[0][j] == 'O') {
                bfs(board,0,j);
            }
            if(board[m-1][j] == 'O') {
                bfs(board,m-1,j);
            }
        }
        // 提取结果
        for(int i = 0; i < m; i++) {
            for(int j = 0; j < n; j++) {
                if(board[i][j] == '.') {
                    board[i][j] = 'O';
                }else if(board[i][j] == 'O') {
                    board[i][j] = 'X';
                }
            }
        }
    }

    public void bfs(char[][] board,int i, int j) {
        Queue<int[]> q = new LinkedList<>();
        q.add(new int[]{i,j});
        board[i][j] = '.';

        while(!q.isEmpty()) {
            int[] t = q.poll();
            int a = t[0],b= t[1];
            for(int k = 0; k < 4; k++) {
                int x = a+dx[k],y = b+dy[k];
                if(x >= 0 && x < m && y >= 0 && y < n && board[i][j] == 'O') {
                    board[x][y] = '.';
                    q.add(new int[]{x,y});
                }
            }
        }

    }
}
